Brake control means



Jan. '19, 1943. w. P. PLACE BRAKE CONTROL MEANS Filed March 29, 1941INVENTQR' RD F- P ACE BY 49 ATTORNEY Patented Jan. 19, 1943 UNITEDSTATES PATENT OFFICE BRAKE CONTROL MEANS Willard P. Place, Wilkinsburg,Pa., assignor to The Westinghouse Air Brake Company, Wilmerding, Pa., acorporation of Pennsylvania Application March 29, 1941, Serial No.385,890

(01. sea- 21) 8 Claims.

This invention relates to brake controlling apparatus, and moreparticularly to an anti-wheelslide control equipment of theelectro-inertia type.

In order to promote maximum braking efficiency and full utilization ofavailable braking power in the operation of modern high speed trains, ithas been proposed to equip railway vehicles with braking systemsincluding automatic anti-wheel-slide control means designed to respondto initial slipping of an excessively braked Wheel for effectingmomentary release of the associated brakes. As is generally understood,the slipping of a wheel occurs when the speed of rotation thereof isreduced below that corresponding to the vehicle speed, or in otherwords, when the wheel is caused to decelerate at a faster rate than thatof non-slipping wheels. In its usual form, the anti-wheel-slide controlapparatus is constructed and arranged to restore the rotative speed of aslipping wheel to that corresponding to the speed of the vehicle in timeto prevent locking of the brakes and consequent sliding of the wheelalong the rail.

In the United States Patent 2,039,701, issued May 5, 1936, to R. J.Bush, and assigned to the assignee of the present application, there isdisclosed an electro-inertia responsive brake control device havingcertain characteristics of an induction generator, and comprising aplurality of field poles carried by a rotary element that is driven atthe speed of a vehicle driving shaft, and a rotor journaled in therotary element and carrying a winding in which a current can begenerated when the rotor overruns the field poles in response toexcessive deceleration of the associated wheel. According to the patent,the wound rotor is designed to operate at synchronous speed with respectto the mechanically rotated field poles under normal braking conditions,and the inertia of the rotor will cause it to slip with respect to thefield poles, and thus to generate a current for actuating suitable brakerelease means, only when the rotary field element is decelerated at arate indicating slip- ,a

ping oi the wheel along the rail. It is desirable to provide forindividual control of the braking force applied to each axle of avehicle, and this result might be achieved by mounting a brakecontrolling generator device of the above type on the journal box at oneend of each axle, so that a direct drive connection could be establishedbetween the axle and therotor of the device. However, all of theelements of the control device would in such case besubjected to theconstant pounding and vibration transmitted through the vehicle wheelsto the unsprung por tions of the truck frame. As a result of continuousshock thus encountered under operating conditions, the necessarilydelicate windings and connections of the rotor, and the severalsupporting bearings as well, might be prevented from serving a desirablylong service life.

It is a principal object of my invention to provide an improvedelectroresponsive brake control device of the above type, whichcomprises a commutator mechanism of simple and sturdy constructionmounted on a journal box, and a separate rotary induction device adaptedto be carried in a remote position on the spring supported body of thevehicle, the latter device being operative through the medium of anelectrically revolving field controlled by the commutator device.

Another object of the present invention is to provide an improvedelectro-responsive brake control means comprising a rotary inductiondevice adapted to be mounted in any convenient, relatively shock freelocation on a vehicle and operative for producing current to operatesuitable brake release means, and having associated therewith anauxiliary rotary contact mechanism or commutator of simple, lightweightconstruction, which is operable by the wheel and axle assembly fordistributing energizing current to the windings of the rotary inductiondevice at a frequency corresponding with wheel speed.

Another object of the invention is to provide an improvedelectro-inertia responsive deceleration and acceleration controlmechanism of the class described, in which a rotating field is producedentirely by electrical means at a frequency determined by the speed ofrotation of the associated wheel.

It is a further object of the invention to provide an acceleration ordeceleration control apparatus including a driving member, electricalmeans for establishing a revolving magnetic-field at a frequencycorresponding with the speed of the driving member, a rotor arranged tooperate therein at synchronous speed under normal conditions, a Windingcarried by the rotor and adapted to supply current to a control circuitin response to slip of the rotor under the force of inertia, and meansresponsive to current in the control circuit for correcting the rotatingcondition of the driving member.

Other objects and advantages of the invention will appear in thefollowing more detailed description thereof, taken in connection withthe accompanying drawing, in which Fig. l is a diagrammatic view of anelementary type of fluid pressure brake equipment with which isassociated a preferred form of brake control means constructed inaccordance with my invention, and

Fig. 2 is a fragmentary diagrammatic view of a modified form ofcommutator which may be used in place of that shown in Fig. 1.

Embodiment shown in Fig. 1

In Fig. l of the drawing, a simplified form of air brake system for avehicle is illustrated diagrammatically, and comprises a main reservoirID, a self-lapping brake valve device II which is connected with thereservoir ID by way of a supply pipe I 2 and which is operative inaccordance with movement of a handle |3 to supply air at a selectedpressure to a straight-air pipe l5, and a brake cylinder device l5 whichcommunicates by way of a branch pipe I! with the straight air pipe. Thebrake cylinder device I 6 is operative to apply braking pressure to avehicle wheel and axle assembly 29 through the medium of the usualfriction brake elements, not shown.

Interposed in the branch pipe I! is a magnet valve device 2| comprisinga casing having a valve chamber 22, which communicates at all times withthe portion of the pipe I! leading to the brake cylinder l6, and whichcontains a double beat valve 24 adapted to control communication to thevalve chamber from th portion of the pipe I! leading from the straightair pipe l5. The double beat valve 24 is normally held in an upperseated position, as shown, under the force of a spring 26, formaintaining communication between the straight air pipe and the brakecylinder, and is adapted for movement to a lower seated position inresponse to energization of a magnet 21 for connecting the chamber 22 toan atmospheric exhaust port 28, as will hereinafter be more fullyexplained.

According to the invention, the wheel and axle assembly 29 hasassociated therewith a commutator device 39, which may be mounted bysuitable means, not shown, on a journal box adjacent the end of theaxle, as indicated in the drawing, or may be mounted on the car truckand operatively connected by a flexible drive with the wheel and axleassembly. As illustrated in the drawing, the commutator device 39comprises a casing structure disposed concentrically of the wheel andhaving mounted therein an insulator block 32 supporting four arcuatemetallic commutator segments 33, 34, 35 and 36, which are fixed atequally spaced positions about the axis of the wheel and axle assembly20. A collector ring 38 is secured to and suitably insulated from theadjacent end of the axle of the assembly 20 and has formed thereon anoutwardly extending contact arm 39, which is adapted to be moved intoand out of engagement with the several commutator seg ments insuccession, during rotation of the wheel and axle assembly. A brush 4|,which may be mounted in a brush holder, not shown, is disposed insliding contact with the ring 38 and is connected to a conductor 42leading to the negative terminal of a battery or other source of directcurrent 43.

A similar collector ring 45 is secured to and insulated from the axle ofthe assembly 20, and carries a contact arm 45 which extends outwardlyand is disposed diametrically opposite the arm 39. The contact arm 46 isthus adapted for engagement with each of the commutator segments 33, 34,35 and 36 in succession, the two contact arms 39 and 46 being arrangedfor engagement with oppositely disposed commutator segmentssimultaneously. A brush 48 is mounted in sliding engagement with thecollector ring 45 and is connected by means of a conductor 49 with thepositive terminal of the battery 43. A normally closed cut-01f switch 44and resistor 41 may be interposed in series with the conductor 42, ifdesired.

The brake controlling means embodying the invention further comprises arotary electro-inertia control device 59, which is preferably carried onthe vehicle body at a point remote from the axle and is designed to havecertain characteristics of both an induction motor and a synchronousmotor. The control device 59 includes a casing 5|, which is adapted tobe mounted in any convenient location on the vehicle where vibration isat a minimum, and may be secured in place by rubber or spring supportingmeans, not shown. Mounted on the interior wall of the casing 5| are fourequally spaced pole pieces 53, 54, 55 and 5B, which carry field windings58, 59, 69 and GI, respectively. The oppositely disposed field windings58 and 69 are connected by means of a conductor 64, and are so wound asto produce opposite or north and south magnetic poles when energized,hereinafter explained. Similarly, the windings 59 and 89 are wound inthe same direction and are connected by means of a conductor in order toproduce opposite poles depending upon the direction of the energizingcurrent. In the form of the invention diagrammatically illustrated, thewinding 58 is connected by means of a conductor ID with the commutatorsegment 33, and the opposite winding 69 is connected by a conductor IIto the commutator segment 35. In like manner the opposite windings 59and 6| are respectively connected to the commutator segments 34 and 36by means of conductors 13 and 14.

The casing 5| of the electro-inertia control device 50 is provided withsuitable bearings, not shown, in which are journaled opposite ends of ashaft 16 which carries a rotor 11, which is shown in the drawing asbeing of bipolar form, and is disposed in concentric relation withrespect to the four pole pieces carried by the casing. The rotor 11 ismade of soft iron or a magnetic alloy, and is provided with a winding89, the terminals of which are connected to suitably insulated collectorrings 8| and 82 carried by the rotor, which rings are mounted in slidingengagement with stationary brushes 83 and 84, respectively.

The winding 88 carried by the rotor 11 is designed to have inducedtherein a control current which, within the scope of the presentinvention, may be utilized for initiating operation of any suitable typeof brake release or rail sanding mechanism. One form of brake releasecontrol means is shown in Fig. 1 for the purpose of iilustration, andincludes the magnet valve device 2| previously described, a battery orother source of electrical energy 81, a pressure switch 88, and amagnetic relay 99, the control circuit for which includes a pair ofconductors 9| connected to terminals 92 of a rectifier assembly 93, anda pair of conductors 94 which are connected respectively to terminals 95of the rectifier assembly and to the brushes 83 and 84 of theelectro-inertia control device 50. The pressure switch 88 may be of anysuitable construction, and as illustrated is arranged for operation toits circuit closing position by the pressure of air supplied to thebrake cylinder branch pipe I! in efiecting an application of the brakes.

Operation When the vehicle carrying the equipment shown in Fig. 1 is setin motion, the wheel and axle assembly begins to revolve and operatesthe commutator device to distribute energizing current to the fieldwindings of the electroinertia control device 650, the windings beingenergized in sequence so as to establish a rotating field to which therotor I1 is adapted to respond by rotating at synchronous speed.Assuming for example that the wheel and axle assembly 20 begins torotate in a clockwise direction, as viewed in Fig. 1, upon engagement ofthe contact arms 39 and 46 with the commutator segments and 33 currentis fed through a circuit including the positive terminal of battery 43,conductor 49, brush 48, collector ring 45, contact arm 46. segment 33,conductor 10, the connected field windings 58 and 6t), conductor II,commutator segment 35, contact arm 39, collector ring 38, brush 4|, andthe conductor 42 together with switch 44 and resistor 41 leading to thenegative terminal of the battery. With the pole pieces 53 and 55 thusenergized as south and north poles, respectively, the flux thereby setup in the rotor 11 pulls that element into pole to pole alignment withthe prevailing magnetic field to maintain the flux at a maximum. As thecontact arms and 39 are then brought into engagement with the next pairof commutator segments 34 and 36, respectively, the other set of fieldwindings in the electro-inertia control device are energized through acircuit including the commutator segment 34, which is now connected withthe positive terminal of the battery 43, conductor "I3, the connectedfield windings 59 and BI, conductor I4, and the commutator segment 36,which is connected with the negative terminal of the battery. It will beapparent that the windings 59 and BI are thus energized to establishsouth and north poles, re-

spectively, causing the rotor 21 to follow and to become aligned withthe pole pieces 54 and 56.

Upon further rotation of the wheel and axle assembly to bring thecontact arm 46 into engagement with the commutator segment 35 andcontact arm 39 into engagement with the segment 33, current is this timesupplied to the windings 60 and 58 in a direction to create north andsouth poles, respectively, thus establishing flux for exerting anotherimpulse turning the rotor T1 in a clockwise direction. Similarly,engagement of the contact arms 45 and 39 with the commutator segments 36and 34 effects reverse energization of the windings 6| and 58. it beingapparent that succeeding pairs of poles are energized in cyclescorresponding with rotation of the wheel and axle assembly 20, arevolving magnetic field is thereby established, and that the rotor ITwill lock in step with the revolving flux to rotate at synchronous speedas determined by the rotary speed of the wheel and axle assembly.

As the rotary speed of the wheel and axle assembly 20 is increased, thefrequency of the alternating current distributed by the commutatordevice 38 to the field windings of the electro-inertia device 53 iscorrespondingly increased, while the rotor 11, in continuing to revolvein synchronism with the revolving magnetic field, acquires momentum. Itwill be understood that so long as the rotor 11 is thus rotated atsynchronous speed, no current will be induced in the winding 80, therebeing no slip or relative motion between the rotor and the revolvingfield. The rotor I1 and other elements of the electroinertia controldevice 50 are so proportioned and arranged that the inertia of therotor, when revolving within the speed range of the vehicle, will notprevent that element from remaining in step or at synchronous speed withrespect to the revolving field under normal conditions of accelerationand deceleration thereof, in accordance with the varying speeds at whichthe wheel and axle assembly 20 is operated.

An application of the brakes may be effected by moving the handle I3 ofthe brake valve device I I into the brake application zone, therebyoperating the brake valve device to supply air under pressure to thestraight air pipe I5 and thence through the branch pipe I! and past thedouble beat valve 24 to the brake cylinder device I6. At the same time,the pressure switch device 88 is operated by the compressed air in pipeI! and assumes its circuit closing position. If the braking power thusapplied to the wheel and axle assembly 20 effects retardation thereof ata normal rate, so that the wheels continue to rotate at the speed of thevehicle without slipping, the force of the rotating flux exerted on therotor 11 of the eleotro-inertia control device 50 continues to besufiicient to hold the rotor in step or at synchronous speed, ashereinbefore explained.

If the wheel and axle assembly 29 is braked too heavily, however, withthe result that the wheel begin to slip and decelerate at an exces siverate, the relatively sudden change in the cycles of rotation of themagnetic field acting on the rotor 11 causes the rotor to pull out ofsynchronism or to overrun the revolving field. When relative motionbetween the rotor TI and the revolving field thus occurs, an alternatingcurrent is induced in the winding 8%), which current is transformed bythe rectifier assembly 93 into direct current for energizing the coil ofthe relay 90.

The contact element 90a of the relay is thereby picked up for closing acircuit which includes the positive terminal of the battery 87, aconductor I08, the contact element 900:, a conductor IOI, the contactelement 88a of the pressure switch 88, a conductor I02, the magnet 21 ofthe magnet valve device 2 I, and a conductor 23 leading to the negativeterminal of the battery. The magnet 27 is consequently energized forshifting the double beat valve 24 to its lower seated position, wherebythe further supply of air under pressure to the brake cylinder I6 is cutoff while the brake cylinder is vented to the atmosphere by way of theexhaust port The braking force exerted by the brake cylinder device I6is thus quickly withdrawn from the wheel and axl assembly 23, which isthen free to resume a speed corresponding to that of the vehicle.

As the rotary speed of the wheel and axle assembly 28 is increased andapproaches the vehicle speed, the correspondingly accelerated revolvingfield of the electro-inertia control device 5!) will once again pick upthe armature T! and rotate it at synchronous speed. This action will befacilitated due to the fact that. since he winding carried by the rotor.II is connected in a closed circuit, any slip of the rotor with respectto the field will be accompanied by the production of flux in the rotordue to the induced current in the circuit, which flux in reacting withthe r volving flux of the field will subject the rotor to a drivingtorque until it again approaches synchronous speed. It will be evidentthat the control device 50 may thus operate in the manner of awound-rotor induction motor during starting and sudden acceleration,before the rotor looks into step with the field.

For certain installations of the brake controlling equipment, it may befound desirable to design and construct the relay 90 in such a manner asto provide it with a slow drop-out characteristic, in order to ensureenergization of the magnet 27 of the magnet valve device for asuflicient interval to effect the desired release of the brakes,regardless of the time during which the relay may be actually energizedby current induced in the winding 80 of the electro-inertia controldevice 59. It will of course be understood that after a slipping wheelcondition has been corrected and the electro-inertia control device 50has been returned to synchronous operation so as to prevent further flowof current in the circuit of the relay S0, the relay contact arm 90awill again be dropped to its circuit opening position for deenergizingthe magnet 21, while the double beat valve 24 will be moved to its upperseated position to permit resupply of compressed air to the brakecylinder device 16.

Embodiment shown in 2 Since it is intended that the operating elementsof the electro-inertia control device 50 be relatively small in size andof light weight construction, it may be desirable to so design theassociated commutator mechanism as to efiect operation of the rotor 11at a speed greater than that of the associated wheel and axle assembly,thereby rendering the rotor operable to store considerable kineticenergy, inasmuch as kinetic energy is proportional to the square of theangular velocity. One means by which this result may be accomplished isillustrated in Fig. 2 of the drawing. in which a commutator mechanism38a is provided as a substitute for the commutator mechanism 30 shown inFig. 1. In the commutator mechanism 30a, the commutator segments aredoubled in number, and comprise in clockwise order, segments 33a, 34a,35a, 38a, 35b, 35b, 33b and 34b, with the contact segments bearing likenumerals connected in pairs to the corresponding conductors I3, 10, Hand 14, in the same manner as has been described in connection withFig. 1. It will be evident that each rotation of the contact arms 46 and39 will effect distribution of energizing current in two cycles to thefield windings of the electro-inertia control device, which willtherefore be operated at twice the speed of the wheel and axle assembly20.

From the foregoing it will now be seen that a control apparatusconstructed in accordance with my invention may be used for detectingand governing acceleration or deceleration of a rotating element such asa car wheel, and comprises a small axle driven commutator, and aseparate, remotely disposed electro-inertia responsive control devicewhich is adapted to be driven by alternating current distributed by thecommutator device. The electro-inertia responsive control device, whichmay be carried on any spring supported member of the vehicle so as to berelatively free from vibration, is somewhat similar in construction to atwo-phase wound-rotor induction motor and includes an inertia responsiverotor normally operable at synchronous speed, as determined by thefrequency of the current distributed by the commutator device, duringwhich time no voltage will be generated in the rotor winding. When therotor is caused to overrun the revolving field electrically produced bythe commutator device, by reason of deceleration of the associatedvehicle wheel at the excessive rate resulting from slipping of thewheel, the resultant electric current induced in the rotor winding issupplied to relay means operative to initiate release of the brakes.

Although one embodiment of the invention and a modification thereof havebeen described in detail, it is not intended to limit the scope of theinvention to those embodiments or otherwise than by the terms of theappended claims.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent, is:

1. A brake equipment for the wheel of a vehicle includingelectro-responsive brake control means operative to regulate the degreeof braking force supplied to the wheel, and anti-wheel-slide meanstherefor comprising a. synchronous motor mounted on a part of thevehicle remote from said wheel and having an inertia responsive woundrotor with a winding connected to said electro-responsive brake controlmeans, and electrical alternator means mounted adjacent said wheel andoperable thereby to supply alternating current to said motor at afrequency corresponding to the rotary speed of said wheel, said rotorbeing constructed and arranged to pull out of synchronous speed and tothereby generate current in said winding upon deceleration of said wheelat an excessive rate.

2. A brake equipment for the wheel of a vehicle includingelectro-responsive brake control means operative to regulate the degreeof braking force applied to said wheel, and anti-wheehslide meanstherefor comprising a synchronous motor mounted on a part of the vehicleremote from said wheel and and having an inertia-responsive wound rotorwith a winding connected to said electro-responsive brake control means,and electrical alternator means mounted adjacent said Wheel and operablethereby to supply alternating current to said synchronous motor fornormally driving said rotor at the same speed as that of the wheel, saidrotor being constructed and ar ranged to pull out of synchronous speedand to thereby generate current in said winding upon deceleration ofsaid wheel at an excessive rate.

3. A brake equipment for the wheel of a vehicle includingelectro-responsive brake control means operative to regulate the degreeof braking force applied to said wheel, and anti-wheel-slide meanstherefor comprising a synchronous motor mounted on a part of the vehicleremote from said wheel and having an inertia-responsive wound rotor witha winding connected to said electroresponsive brake control andelectrical alternator means mounted adjacent said wheel and operablethereby to supply alternating cur rent to said synchronous motor fornormally driving said inertia responsive rotor at a higher speed thanthat of said wheel, said rotor being constructed and arranged to pullout of synchronous speed and thereby to generate current in said windingupon deceleration of said v -ieel at a rate corresponding to wheelslipping.

4. In a brake controlling equipment for a wheel of a railway vehicle, incombination, brake means associated with the wheel, means for effectingan application of the said brake means, electro-responsive means foralso controlling the operation of said brake means, relay meansresponsive to current in a control circuit for energizing saidelectro-responsive means, and means for generating current in saidcontrol circuit in response to slipping of the wheel including aninertia responsive rotor having an auxiliary winding connected in saidcontrol circuit, stationary field winding means adapted to be energizedby alternating current to produce a revolving field for normally drivingsaid rotor at substantially synchronous speed, said rotor and fieldwinding means being located on a part of the vehicle spaced from saidwheel, and alternator means remote from said other elements and operabledirectly by the wheel to energize said stationary field winding means ata frequency corresponding to the rotative speed of said wheel, saidrotor means being adapted to overrun said revolving field upon a suddenchange in frequency.

5. In a brake control equipment for regulating the degree of applicationof the brakes on a wheel and axle assembly of a vehicle, the combinationof electro-responsive control means including a normally deenergizedcontrol circuit, an electro-inertia device carried on the body of saidvehicle in a position remote from said wheel and axle assembly, saiddevice comprising a plurality of field windings and a magnetic rotorassociated therewith, said rotor carrying an auxiliary winding that isconnected to said normally deenergized circuit, a source of electriccurrent, and a commutator device operably connected to the wheel andaxle assembly and driven thereby for distributing current from saidsource to said field windings in sequence for establishing a revolvingflux, whereby said rotor is normally operated at synchronous speedcorresponding with the rotative speed of said wheel, said auxiliarywinding being adapted to deliver an induced current to said controlcircuit when said rotor pulls out of step with said revolving field upondeceleration of said wheel at an excessive rate.

6. In a brake control system for a vehicle having a wheel, incombination: a binary electroinertia control apparatus for detectingsudden deceleration of said wheel, said apparatus comprising electricalcommutator means associated with the wheel for distributing currentthrough a plurality of circuits, and remotely disposed electro-inertiamechanism including means energized by said current for producing anelectrically revolving magnetic field having a frequency determined bythe wheel speed, an inertia responsive rotor mounted within said fieldand normally operable thereby at synchronous speed, and a windingcarried by said rotor; and electroresponsive brake control means adaptedto be energized by current induced in said winding when the inertia ofsaid rotor causes it to slip out of step with respect to saidelectrically revolving field.

7. In a wheel brake equipment, in combination, electro-responsive brakecontrol means, a control circuit therefor, a source of alternatingcurrent including a commutator device driven by the wheel, and anelectro-inertia responsive control device adapted to be mounted at alocation remote from said commutator device and comprising a fieldwinding responsive to the current supplied from said commutator devicefor producing a revolving fiux, an inertia responsive Ot r normallyoperable thereby at synchronous speed, and a winding on said rotorconnected with said control circuit for generating current in responseto slip of said rotor out of synchronous operation with respect to therotating flux of said field winding.

8. In a brake control system for a vehicle having a wheel and brakingmeans therefor, in combination: electro-responsive brake control means;a normally deenergized control circuit therefor; and a two-partdeceleration control apparatus including an electrical deviceoperatively connected with said wheel for delivering alternating currentat a frequency proportional to Wheel speed, and a separate rotaryinertia device adapted to be carried on a portion of the vehicle remotefrom said wheel and thus relatively free from vibration thereof, saidrotary inertia device including a field winding energized by saidelectrical device for establishing a magnetic field varying in accordance with wheel speed, and an inertia responsive rotor operative insaid field and having a winding arranged to supply current inducedtherein to said control circuit in response to slip of said rotor out ofstep with said field under the force of inertia.

WILLARD P. PLACE.

